Abstract
The present study is a trail to integrate the phycoremediation and bioenergy production from microalgal species cultivated in the dairy wastewater (DWW). Higher biomass productivities for Chlorella pyrenoidosa (24.44 ± 8.02 mg L-1d-1), Anabaena ambigua (23.64 ± 5.69 mg L-1d-1) and Scenedesmus abundans (18.72 ± 2.06 mg L-1d-1) were recorded in 3:1 DWW over the control. The microalgal species have effectively reduced the BOD by 56%, COD by 77%, nitrate by 88%, and phosphate by 85% following 25 days of the cultivation in the 3:1 DWW. The total lipid content was 10.36, 13.13, and 16.93% of dry matter of biomass in C. pyrenoidosa, A. ambigua, and S. abundans, respectively following 25 days of cultivation in the 3:1 ratio of DWW. The biochemical characterization revealed that the protein content was 21.8% in C. pyrenoidosa, 17.73% in A. ambigua and 34.06% in S. abundans. The estimation of theoretical methane potential suggested that the microalgal species have the desirable possibility of biogas generation. The results have marked the achievability of an integrated process for the remediation and bioenergy production by the employment of microalgal species.
Highlights
Efforts for the development of sustainable energy sources are under fierce global development as the petroleum reserves are finite and have reached a pinnacle
In the 3:1 ratio of dairy wastewater (DWW) (3 parts of DWW and 1 part BG-11 medium), maximum chlorophyll content shown by C. pyrenoidosa at 12th day was 97.83 ± 6.72 μg m l−1 followed by A. ambigua (85.65 ± 4.24 μg m l−1 at 7th day) and S. abundans (70.09 ± 0.88 μg m l−1 at 7th day) (Figure 1)
C. pyrenoidosa remained in the exponential phase for 168 h of growth (Figure 1A) whereas A. ambigua and S. abundans remained in the log phase for 144 h of growth for all the ratios of DWW (Figures 1B,C)
Summary
Efforts for the development of sustainable energy sources are under fierce global development as the petroleum reserves are finite and have reached a pinnacle. The extent of industrialization and the pressure exerted by the ever-growing population has resulted in the release of a gigantic amount of wastewaters which are the by-products of various agricultural, commercial, domestic and industrial activities into the environment. The dairy industry is one of the most polluting industries in terms of the effluent volume generated and, in terms of the nature of the effluent. The annual production capacity of Indian dairy industries is approximately 5.5 × 10.66 Kl. It is estimated that 8.7 cubic meters of water per kiloliter of milk produced are consumed to the generation of 6.0 cubic meter of water waste (Annual report, central pollution control board). The wastewater generated includes the production line cooling water, domestic wastewater, acid whey and sweet whey which lead to the change in the quality and quantity of wastewater. It is reported that the sweet whey is the most polluting effluent due to its biochemical composition, i.e., rich in organic matter
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